The absence of DNAM-1 on donor cells maintains GVL effects. (A) Lethally irradiated B6C3F1 or BALB/c mice were transplanted with 5 × 10⁶ BM and 2 × 10⁶ or 0.5 × 10⁶ T cells, respectively, from B6.Foxp3.GFP mice. The expression of DNAM-1 or TIGIT was analyzed on each described T-cell subset from mesenteric lymph nodes at day 10 and from naive mice. Data are representative of 2 to 3 replicate experiments. The same pattern of staining was seen in T cells from spleen and peripheral lymph nodes (not shown). (B) 5 × 10⁶ BM and 0.5 × 10⁶ T cells from B6.WT, B6.DNAM-1^−/−, B6C3F1, or B6D2F1 mice with 5 × 10⁶ P210^luc+ or 5 × 10³ P815^luc+ tumor cells were transplanted into lethally irradiated B6C3F1 recipients (upper panel) or B6D2F1 recipients respectively (lower panel). Representative FACS dots of CD155 expression on each tumor cell line (left), leukemia death (middle), and GVHD death (right) are shown. Data shown with P210^luc+ are combined from 3 replicate experiments (n = 21 to 22 per T-cell–replete group and n = 11 in syngeneic control). P < .0001, B6C3F1 vs B6.WT or B6.DNAM-1^−/−; P = .94, leukemia death of B6.WT vs B6.DNAM-1^−/−; P = .57, GVHD death of B6.WT vs B6.DNAM-1^−/−. Data shown with P815^luc+ are combined from 2 replicate experiments (n = 16 per T-cell–replete group and n = 8 in syngeneic control). P < .0001, B6D2F1 vs B6.WT or B6.DNAM-1^−/−; P = .46, leukemia death of B6.WT vs B6.DNAM-1^−/−; P = .0082, GVHD death of B6.WT vs B6.DNAM-1^−/−. Fisher’s exact test confirmed that there was a significant relationship between GVHD death and group (P = .007).